Wait as late as possible to assign ClipIds

This will allow Servo to create ClipScrollNodes later during display
list construction, which will be necessary once rounded rectangles
are removed from the LocalClip structure. Instead of keeping track
of the ClipId of each ClipScrollNode, we keep track of its index in an
array of ClipScrollNodes. This will allow us to access them without a
hash lookup.

1 files changed, 3 insertions, 4 deletions

diff --git a/components/layout/traversal.rs b/components/layout/traversal.rs
index 077e43fb45c..2905157db3c 100644
--- a/components/layout/traversal.rs
+++ b/components/layout/traversal.rs
@@ -313,9 +313,8 @@ impl<'a> BuildDisplayList<'a> {
         let parent_stacking_context_id = self.state.current_stacking_context_id;
         self.state.current_stacking_context_id = flow::base(flow).stacking_context_id;
 
-        let parent_clip_and_scroll_info = self.state.current_clip_and_scroll_info;
-        self.state.current_clip_and_scroll_info =
-            flow.clip_and_scroll_info(self.state.layout_context.id);
+        let parent_clipping_and_scrolling = self.state.current_clipping_and_scrolling;
+        self.state.current_clipping_and_scrolling = flow.clipping_and_scrolling();
 
         flow.build_display_list(&mut self.state);
         flow::mut_base(flow).restyle_damage.remove(REPAINT);
@@ -325,6 +324,6 @@ impl<'a> BuildDisplayList<'a> {
         }
 
         self.state.current_stacking_context_id = parent_stacking_context_id;
-        self.state.current_clip_and_scroll_info = parent_clip_and_scroll_info;
+        self.state.current_clipping_and_scrolling = parent_clipping_and_scrolling;
     }
 }